Mainspring for watches, clocks, etc.



Aug. 15, 1933. J D so 1,922,921

MAINSPRING FOR WATCHES, CLbCKS, ETC

Filed Aug. 26, 1952 INVENTOR v WITNESSES 07721071 JoVndenmm I I BY ifilf 9 ATTORNEYS Patented Aug. 15, 1933 UNITED STATES PATENT OFFICE 3 Claims.

This invention relates generally to the class of springs employed as motive power, and while not necessarily restricted thereto, refers more particularly to an improvement in mainsprings for 5 watches, clocks or the like.

The invention aims for its principal object to provide an improved spring of the character set forth, by virtue of which greater power is obtained from an improved spring of the same size as the ordinary spring or equal power is obtained from an improved spring of a smaller size than the ordinary spring.

The invention further resides in an improved spring of the indicated character which is comparatively simple in its structure, costs but little more than the ordinary spring and which is highly eflicient in its purpose.

With the aboverecited and other objects in view, reference is had to the following description and accompanying drawing, in which there is exhibited one example or embodiment of the invention, while the claims define the actual scope oi the same.

In the drawing:

Figure 1 is a plan view of a watch spring constructed in accordance with the invention and illustrating the same located in the spring barrel.

Figure 2 is an enlarged cross sectional view taken approximately on the line indicated at 2-2 in Figure 1.

Referring to the drawing by characters or reference, A designates generally a watch or clock spring barrel, B the shaft, and C the improved spring, which is normally 0! cross curved, bowed or concave-convex cross sectional configuration throughout the major or entire length or the spring body instead of being normally flat, as has heretofore been customary. By providing the spring body of cross curved or bowed cross sectional configuration so that it inherently assumes said cross sectional curve, it will be round that more power will be derived from the same thickness than is possible from a fiat spring, or a spring body of considerably lesser thickness will have greater strength and afford greater power than a corresponding flat spring. In use in watches or clocks, this is a distinct advantage, in that there will be aflorded in the spring barrel a greater space to permit of greater expansion of the spring and a longer run of the watch from a single winding before the spring power is exhausted. Furthermore, by means of a concave-convex spring which gives the same strength and power of a fiat spring which is thicker, a spring or greater length may be employed without requiring more space in the spring barrel, which also contributes toward a longer running of the watch on a single winding. By constructing the spring in this manner, it will also be found that space is economized where it is desirable to produce watches of very small sizes.

Preferably, the spring is arranged in the spring barrel with the concave side of the convolutions disposed outwardly and the convex side disposed inwardly, as clearly illustrated in Figure 2 of the drawing, and it will be found that when the spring is wound, the inner convolutions will have a tendency to flatten out while the outer convolutions will be progressively curved to a greater degree toward the outer end of the spring. As the spring unwinds, the convolutions inherently return to their normal curvature, thereby adding to the power developed by the unwinding of the spring convolution.

While there has been illustrated and described a preferred embodiment of the invention, it is to be understood that this is merely descriptive of one form, and that variations and modifications which fall within the range of the claims may be resorted to when desired.

What is claimed is:

1. A spring motor spring comprising a resilient body of concavo-convex cross sectional configuration extending across the entire width of the body, 85.

2. A spring motor spring comprising a resilient body of concave-convex cross sectional coniiguration extending across the entire width of the body having the convex side disposed inwardly.

3. A spring motor spring comprising a resilient body inherently bowed transversely and capable of being flattened when wound up.

. ANTON J. ANDERSON. 

